Extend README/documentation by datatypes

[linuswagner]

From reading the readme, it isn't obvious what the structure of the parameter datasets for model and trainer function is.
This should be explicitly stated to ensure code is compatible with nnfabrik standards from the beginning.
When reading the examples, it seems like it's simply a torch.utils.data.DataLoader object.

[ArneNx]

That is a very good point.
Please take a look at PR #83 and maybe add some suggestions there if you like.

[ArneNx]

I assume this issue is resolved by PR #83, right? I'll go ahead and close it then.
Feel free to reopen if there is more we should do about this.